Research
Sierra open-sources Hyper-τ-bench, an evaluation of models that build customer-service agents
On September 8, 2026 Sierra published Hyper-τ-bench, a long-horizon evaluation that measures whether a model can build a customer-service agent rather than only act as one. A developer agent works in a sandboxed workspace with a simulated business's records and a simulated client it can message, must recover the requirements and turn the business's actions into tools, and the finished agent is then tested on held-out tasks the developer never saw. Sierra says it is open-sourcing the benchmark, with code in the sierra-research/hyper-tau-bench repository, a public leaderboard, and a paper on arXiv; the post does not state a license. USASI has not run the benchmark.1
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USASI. (2026, October 13). Sierra open-sources Hyper-τ-bench, an evaluation of models that build customer-service agents. United States of America Superintelligence. https://unitedstatesofamericasuperintelligence.com/news/sierra-open-sources-hyper-tau-bench/
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@misc{usasi_news_sierra_open_sources_hyper_tau_bench,
author = {{USASI}},
title = {Sierra open-sources Hyper-τ-bench, an evaluation of models that build customer-service agents},
year = {2026},
month = oct,
howpublished = {\url{https://unitedstatesofamericasuperintelligence.com/news/sierra-open-sources-hyper-tau-bench/}},
note = {United States of America Superintelligence. Last updated 2026-10-13}
}The date is when this page was last updated. Add the date you read it if your style needs one.